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Poster: robinia Date: Sep 9, 2006 4:46pm
Forum: etree Subject: question: converting mp3 > CDA > mp3

just wondering-
back before I knew any better I burned some SKB mp3s from digitalsoundboad to Audio-CD. Being small lossy files (originally) I would like to return them to mp3 format...

Will these tracks return to the same 128kbps quality? Are they a 128 conpression of the original 128 compression?
Does this make them 64k?
Presumably ripping them as WAV gets the original "128" quality...


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Poster: greenone Date: Sep 9, 2006 7:45pm
Forum: etree Subject: Re: question: converting mp3 > CDA > mp3

They definitely won't be the same files as the original ones; my guess is that they'll be somewhere between the original 128's and the original 64's (if such a thing existed).

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Poster: xtifr Date: Sep 10, 2006 5:53am
Forum: etree Subject: Re: question: converting mp3 > CDA > mp3

MP3 compression does two things. First, it throws away some high frequencies. In theory, these are too high to hear, but in practice, it turns out that they are an important component of overtones -- you may not be able to hear the frequency, but you can hear its effect on other frequencies. This is why cymbals are often the thing most affected by MP3 compression.

After it does that, it kinda "smears" the rest of the sound a bit, to "rub off" some of the sharp edges and make the whole thing compress better.

Now, for the first part--your high frequencies and overtones are already gone, and there's no getting them back. Which is actually good news--you don't have to worry about that part getting any worse. But trying to re-compress with mp3 will result in another round of "smearing". So the result will be worse. Not 64k-quality worse, but definitely worse. Although it will probably compress better the second time. :)

If you have any way to get the original mp3s back, it will be much better than recompressing them!

This post was modified by xtifr on 2006-09-10 12:53:56